1. Field of the Invention
The present invention relates to a polarographic densitometer for measuring the density of ions or gas components of the specimen in liquid or vapor phase.
2. Prior Art
Previously known in the art as a kind of densitometer for measuring the density of ions or gas components in specimen when it is in liquid or vapor phase is a chlorine meter in which a pair of electrodes is provided each made up of different metals, said electrodes are immersed in the liquid specimen and the residual chlorine is reduced on the surfaces of the electrodes to develop an electro-motive force between the electrodes, on the basis of which the density of chlorine in the liquid is determined (refer to e.g. Patent Document 1).
The chlorine meter as disclosed in Patent Document 1 includes a pair of electrodes: one is made up of a platinum wire and the other is a silver wire. The silver wire electrode is provided with a silver chloride coating at such portion thereof that is to be immersed in the liquid. The pair of electrodes forms a sensor which is immersed in the liquid specimen (e.g. tap water) to allow chlorine in the liquid to be reduced at the surfaces of the electrodes. Then, electric current flows between the electrodes to develop an electro-motive force in proportion to the density of chlorine in the liquid, on the basis of which the density of chlorine is determined.
Patent Document 1: Japanese Patent Laid-Open No. 2002-214220
However, the chlorine meter, as described above, is defective in that due to instability in reaction between the metal electrode and the liquid under test there is less repeatability and linearity provided in relation between potential on the electrodes and the density of certain material and it takes longer period of time for performing measurement.
In view of the above an object of the present invention is to solve the problems in the prior art, as described above, and to provide an improved polarographic densitometer having capability of measuring with higher precision, in reduced time and with highly effective.